more water changes generally equate to better growth and overall condition. it doesnt hurt and has numerous benefits. when people do water changes properly, they usually notice a very apparent in the appearance of the water as well as an improvement in the fish. they may seem fine without the water changes, but they will do even better with them. it may not seem broken yet, but with fish by the time it is apparrently broken, the tank is too far gone to save everybody. its kind of like preventative maintenance on a car. if you never change the oil, it wont be 'broken' until it is very broken. you save money, stress, and time if you just do the preventative maintenance.